Colored lubricating oil



Patented Oct. 15, 1935 UNITED STATES COLORED LUBRICATING OIL Frederick Stanley Clulow, Martinez, Calif., as-

signor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application August 29, 1932, Serial No. 630,785

1 Claim.

This invention relates to lubricating oils and is more particularly concerned with colored lubricating oils.

The characteristics of lubricating oils are determined by the origin of the crude from which the oils were derived and by the refining treatment whereby finished oils were produced. As a result of the improved methods of treatment, the lubricating oils of excellent qualities can be and are manufactured in the industry. The various properties upon which lubricating oils are graded are not apparent, however, from the exterior appearance of the oil samples, but can only be ascertained by a number of more or less complicated tests.

It is well known in the trade, that the ordinary retail purchasers of lubricating oils, while relying upon the trade names and trade marks under which the products are marketed, still have a tendency to prefer the oils having more attractive appearance, so that, when choosing between two lubricating oils of similarly high quality, as to gravity, Co-nradson carbon, viscosity-temperature relationship, and flash point, but differing in color, one normally prefers the oil having a more attractive appearance, characterized by a red tint, when oil is viewed against a source of light, and a greenish fluorescence produced by reflected light. These desirable color characteristics of lubricating oils are frequently either destroyed by an intensive treatment of the raw stock, or the constituents producing them are substantially removed during various refining processes to which the oil distillates are subjected, or the original raw oils, from which the lubricating distillates are derived, may be deficient in the color producing constituents.

It is the object of this invention to provide an improved, efficient and economic method for imparting the desirable color characteristics to lubricating oils.

In carrying out my invention in practice I use, as a source of the coloring matter, a pitch produced by oil gas manufacturing processes, wherein a petroleum, or other hydrocarbon or carbonaceous distillate, or residue, is injected into an alternatively heated chamber packed with a mass of refractory material and decomposed at temperatures above 1400 F. in the presence of steam and under about atmospheric pressure, after which the reaction products are cooled, and the pitch separated from other more volatile substances.

The resulting pitches have been found to be far superior for the oil coloring purposes than any other carbonaceous materials heretofore similarly used in the art. They contain higher concentrations of the coloring bodies and consequently can be more effectively used. In the following description and claim of my invention the pitch produced by the oil gas manufacturing 5 process above referred to is termed an oil gas pitch. Although various grades of this material may be used for the purposes of my invention, I prefer to use the oil gas pitch of the following properties. 10

Penetration at 77 F., (A. S. T; M. D535) 35-45 Softening point, B. & R., F., (D36-26) -130 Flash, 0. 0., F. (D92-24) 325+ B. S. & W. (A. S. T. M. 300.2) not more than 15% 15 The process of coloring lubricating oils according to my invention consists of transferring the coloring substances from the oil gas pitch to a refined lubricating oil by either directly contacting the pitch and the oil at a suitable temperature, assuring a thorough contact of the two materials, or extracting the coloring substances from the pitch with a suitable solvent, such as a As an alternative method of transferring the 35 coloring constituents from the oil gas pitch to a lubricating oil distillate I have successfully employed a method consisting of extracting these constituents from the pitch with a relatively low boiling solvent having a low viscosity, such, for example, as benzol, gasoline, kerosene, various naphthas, and the like, or carbon bisulfide, or carbon tetrachloride, and similar substances, separating the insoluble portion of the pitch from the extract, blending said extract with the lubri- 45 eating oil to be colored, and then removing the solvent by distillation at the temperatures not exceeding 500 F.; often, it may be advisable to carry out this distillation under reduced or subatmospheric pressure. Upon substantially com- 50 plete removal of the solvent from the oil by this distillation step the coloring substances remain in the oil imparting to it the desirable color and outertone but not affecting to any appreciable extent its other physical, properties, such as grav- 55 ity, viscosity, flash pointand Conradson carbon.

The extracting or dissolving of the coloring substances from the gas oil pitch with either of the following solvents: the lubricating oil to be colored, or one of its component portions, or one of the extraneous solvents mentioned hereinbefore, is usually followed by a step for separating the insoluble residue, which tends to settle out of the particular solvent employed. I have found that an ordinary settling step along, or, if desired, combined with centrifuging and/or filtering steps, is entirely satisfactory for removing the last perceptible amounts of insoluble material from the colored solvent.

I have discovered that the lubricating oils colored by my process normally require no chemical after-treatment, because no objectionable effect is produced by the transfer of the oil coloring bodies from the oil gas pitch to a lubricating oil. It may be desirable sometimes, however, to chemically treat a colored oil, for some reason not necessarily related to the coloring step of refining the oil without destroying the imparted color, in which case the desired treatment can be carried. out without departing from the spirit and scope of this invention.

The quantity of the oil gas pitch used in my process is relatively small, but it may vary within rather wide limits to suit requirements of the individual cases, and can be experimentally determined to produce the desired color effect.

I claim as my invention- As a new article of manufacture: the compound of a mineral oil and an oil-coloring portion of the pitch from pyrolytic decomposition at substantially atmospheric pressure of a hydrocarbon oil in a chamber packed with a mass of refractory material heated to a temperature above 1400 F. and in the atmosphere of steam, said pitch-like product having a flash point of at least 325 F.

FREDERICK STANLEY CLULOW. 

